It has been previously disclosed, in my U.S. Pat. No. 3,742,093 granted June 26, 1973, that a substantially insoluble liquid may be separated by pressure as a liquid from a plasticized material containing a polymer or polymer mixture. According to this disclosure, polymeric materials are mixed, worked and conveyed by a section of a screw extruder through a high pressure region, and a liquid is removed from the mixture downstream of this high pressure region. Another high pressure region is provided downstream of the liquid removal point. The liquid which is to be removed may be one having a relatively high latent heat of vaporization, which tends to volatilize under the conditions of temperature and pressure that are present within the housing. However, in accordance with the method of the aforesaid patent, an outlet is provided for the liquid, including a valve or other means for maintaining a high pressure on the liquid, thereby maintaining the liquid in liquid form as it is forced out of the extruder, thereby preventing substantial quantities of the liquid from flashing into vapor during the removal step.
Processes in accordance with the aforementioned Skidmore U.S. Pat. No. 3,742,093 are ideally suited for the manufacture of rubber-polymer mixtures such as acrylonitrile-butadiene-styrene copolymers, for example. Dispersed particles of polymer in water may be introduced as a latex into a hot, plasticized polymer mixture and they may be mixed in such a manner as to coagulate the latex emulsion, liberating water which is retained in the liquid state and which is removed through a liquid outlet under such conditions of temperature and pressure that it remains liquid and thereby does not absorb its latent heat of vaporization from the contents of the extruder. However, it has heretofore been considered that it was necessary to introduce the latex emulsion into another polymer such as the aforementioned copolymer, for example, in order to effect the continuous coagulation of the latex. It was apparent that the presence of the polymer or polymer mixture had a significant effect in causing and in maintaining the continuous coagulation of the latex emulsion.